1. Technical Field
The present invention relates to a communications: relay apparatus for relaying communications between an electronic control unit (ECU) connected to the apparatus via an in-vehicle local area network (LAN) and an external device connected to the apparatus via a communication path different from the in-vehicle LAN.
2. Related Art
An immobilizer, as disclosed in Japanese Patent Application Laid-Open Publication No. H08-30873, is a vehicle-mounted anti-theft system, which authenticates a vehicle user with an encrypted code received from a user's key and allows an engine to start only when the user is successfully authenticated. Use of the immobilizer can prevent vehicle theft, for example, even when a vehicle's door is forcibly opened.
An ECU serving as the immobilizer (referred herein to as an immobilizer ECU) is connected to an in-vehicle LAN, such as a controller area network (CAN) or the like. In recent years, an increasing number of vehicles provided with a dedicated port for connecting an external tool to the in-vehicle LAN are circulating. In each of them, the external tool communicates with the immobilizer ECU via such a dedicated port to test the immobilizer ECU or to reprogram the immobilizer ECU for correcting a flaw therein or for version upgrade.
In recent years, however, a devious tool (known as an “immobilizer cutter”) capable of deactivating the anti-theft function of the immobilizer in a short time has been in circulation. The devious tool can be connected to the in-vehicle LAN via the dedicated port to access the immobilizer ECU and can deactivate the anti-theft function by reprogramming the immobilizer ECU.
As above, the reprogramming of the immobilizer ECU via the in-vehicle LAN may be misused for vehicle theft. In addition, the immobilizer ECU may be tampered with in a similar manner.
In consideration of the foregoing, it would therefore be desirable to have a communications relay apparatus capable of preventing unauthorized reprogramming of an ECU.